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One Page Tip #9
Fuel Flow Meter Accuracy Checks

Regulatory references: 

Part 75 Appendix D, §, and 2.1.7, P75 Policy Manual Section 23 (Appendix D), Policy Manual Question 9.12 (Appendix D and E Orifice Fuel Flowmeter Calibration) and StackVision User Guide. 


The fuel flow meters used under the Appendix D reporting protocol require periodic accuracy checks to verify the quality of the flow data they are reporting.  There are many different types of fuel flow meters which are used in today’s industries, which also means the acceptable methods for calibrating these systems and verifying the accuracy these devices, is also wide ranging. 

Each facility should have an established procedure for conducting these calibration checks.  This procedure should also be found in the Quality Assurance Quality Control plan covering the CEMS at the facility. 

Points to remember and use during the fuel flow meter accuracy checks:  

  1. Typically, P75 requires a calibration check must be performed within four “fuel flow QA operating quarters”.  A QA operating quarter is both fuel-specific and monitor specific.  It also means that if a specific fuel was burned for ≥ 168 hours in a calendar quarter, that calendar quarter is a QA operating quarter.  If a fuel monitoring system did not operate enough to qualify as a “QA operating quarter” then the deadline for performing the next calibration check can be delayed until that fourth QA operating quarter is achieved. 
  2. Some types of fuel flow meters can be tested or checked for their accuracy while in place. To use this method, another meter of proven accuracy is connected in series to the fuel lines and the same fuel passes through both meters for a given period.  The amount of fuel recorded by both systems is recorded and compared. 

  3. Some types of fuel flow meters can be removed and tested off site.  When they are removed for service and testing, either another meter can be rotated into its’ place or returned to its’ original location.  The off-site testing needs to provide documentation that the metering system has been tested to an accuracy of not > 2.0%. 

  4. Some systems associated with orifice, nozzle and venturi-type fuel flowmeters that conform to AGA Report No. 3, the owner or operator may opt to certify the meters by calibrating the transmitters (or transducers) using NIST-traceable equipment, in lieu of calibrating the meters with a flowing fluid.  If this option is chosen, use the Wizard described in step 7. 

  5. No matter whatever calibration or testing method was used, you need to document and show that the overall accuracy of the metering system is not > 2.0% accuracy. 

  6. The duration for performing your next accuracy test can be extended if you utilize a “Fuel Flow to Load” check.  See the One Page Tip for this topic later in this document. 

  7. In StackVision, you need to prepare test record for the calibration check just performed.  In SV, click on Tools > QA and Certification > Fuel Systems to open the Fuel System Tab. Click the Flowmeter Accuracy or Transmitter Transducer tab.  Click on the Add icon (  ) to launch Wizard for Creating Fuel Flowmeter Accuracy or Transmitter Transducer Tests.  For details on using this Wizard, see the StackVision User Guide related to this topic. 

  8. Do you need to update your fuel flow metering system calibration procedure?  Are there any lessons learned or better steps to follow that you uncovered during this round of testing? Update them now to improve your chances for success. 

For questions, suggestions, or for a general chat, please do not hesitate to contact me.

Download the PDF document here.

Jon Konings, Senior Regulatory and Reporting Engineer, ESC

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